Responses
ik this is not what you're looking for but this kinda has the same plot/theme.
https://www.mangago.zone/read-manga/a_dick_scovery/
(ngl at first, i actually thought this is what you're looking for lol)
yankee/delinquent yaoi. uke is the strongest at school oor something like that, he avoids going to the toilet with other people I think is bc he have a tiny dick? im not so sure. he met the seme, a regular guy with big dick. I cant remember the title